Multipressure gear pump



June 6, 14933. E. J. svENsoN 1,912,738

MULT I PRES SURE GEAR PUMP Filed March 22, 1950 2 Sheets-Sheet 1 .w Qq

V N @hm m @u W l N E R1 S i 5 w t @l m R i S2-SJ m 'l sg June 6, 1933. E. J. svENsoN MULTIPRESSURE GEAR PUMP Filed March 22, 1930 y 2 Sheets-Sheet 2 w m 5. A QN `NN v m m @Cw EN www K ma Y p Q www., I 1 j om am@ )mw om (am Nw )Nm Patented June 6, 1,933v

MULTIPRESSURE GEAR PUMP .Application filed March 22, 1930. Serial No. 437,959.

My invention relates generally to fluid propelling mechanisms, and vmore particularlyl to propelling devicesof the gear pump type.

` In conventional types of gear pumps, two meshing gears are mounted within a suitable chamber and fluid is introduced within the chamber on one side of the gears, the teeth in said gears serving to carry the fluid tothe opposite side of the chamber, at which point l0 the fluid is subjected to pressure and is usually passed through a suitable outlet port. Considerable difficulty has been experienced heretofore in using such devices as the result of the development of heat due to the compression of the portion of the fluid which is j trapped between the meshing teeth. In an endeavor'to meet this situation, the teeth of the gears have been configurated so as to present certain clearances which enable the fluid gathered between the meshing teeth to be returned to the low pressure side of they pump chamber. Obviously, this icy-passing or v{je-delivery of fluid to the intake side of "thegpump greatly reduces the propelling e-ffici'ency of the device. In my copendlng aplfplication, Serial No. 430,868, filed February 211:;1930, I have disclosed a fluid, propelling mechanism of the gear pump type which relates `ina general way to the structure shown iif'my present application in that I have shown means in the form of radial ports or paf'S'Szages for directing fluid away from the meshing teeth to relieve against the developnient of` heat producing fluid pressures. While my present invention contemplates the use of radial ports for relieving against f fluid pressures, it also contemplates the provision of additional advantageous features notshownor suggested in' my above men- 40 tioned co-pending application.

Heretofore it has been possible to subject fluid at the discharge side of the meshing gears in a pump to a given pressure, and this fluid is usually conducted through a suitable duct or pipe to the point of use. However,

my present invention contemplates the rovision of a fluid propelling mechanism o the gear pump-type which is not only capable of subjectlng fluid to apressure at the discharge side of the pump, as above set forth,

fluid at different pressures may be supplied from a pair of meshing gears without the necessity of introducing any additional rotating parts, or, in other words, without complicating the structural arrangement of said l gears.

A-further, object is to provide a fluid propelling mechanism of the above mentioned type in which the fluidsalvaged from between the meshing gear teeth may be effectively controlled as by means of a suitable valve mechanism.

' Still another object of my present invention is to reduce to a minimum the possibility vof developing heat in the fluid which is trapped between the meshing gear teeth, and to this end I propose to provide a recess along the outer surfaces to certain of the gear teeth,

`wh ich will serve to facilitate the flow of fluid toward the radial ports.

More specifically, my invention contemplates the provision of a gear pump construction, in which the fluid from between the meshing gear teeth may be salvaged and conducted to a point centrally positioned with respect to one of the gears, and from this point may be directed as desired independently of the fluid which is withdrawn from the usual discharge side of the pump.

In addition to the above mentioned ad-l vantageous structural characteristics, my in vention contemplates the provision of a central oscillatory valve within one of the meshing gears which may be adjusted to vary the displacement of salvaged fluid, and which will serve to direct said salvaged fluid to any point externally of the pump. Y

These and numerous other objects and advantages will be more apparent from the following detailed description when considered in connection with the accompanying d1..w ings, whereingure 1 is a side elevational view of a Huid propelling mechanism which is constructed in accordance with the teachings of my present invention Figure 2 is a vertical transverse sectional view of the mechanism taken substantially along the line 2 2 of Figure 1;

Figure 3 is a vertical transverse sectional view of the device, said section being taken substantially along the line 3 3 of Figure 2;

Figure 4 is a fragmentary transverse sectional view of the lower gear and the associated valve member, said view being taken substantially along the line 4 4 of Figure 2 for the purpose of more clearly disclosing the radial ports or ducts which extend to the outer extremities of the gear teeth;

Figure 5 is a plan view of the valve member detached froln the lower gear; and

Figure 6 is an enlarged detail View of the meshing teeth disclosing the manner in which the gear teeth are specially constructed so as to eliminate the necessity of employing the usual clearance, this construction being made practical as a result of the provision of the pressure relieving radial ports. p

Referring now to the drawings more in detail wherein like numerals have been employed to designate similar parts throughout the various figures, it will be seen that one embodiment of my invention resides in the provision of a mechanism which includes a central housing or casing 10 and a pair of spacer plates 12 and 14 and casings or end sections 16 and 18. The spacer plate 12 properly positions the end casing 16, and the spacer plate 14 is interposed between the central section 10 and the end casing 18, as clearly shown inFigure 2. These parts are secured together by means of suitable screws 20 and are maintained in proper alinement by means of suitable dowel pins 22. The spacer plates 12 and 14 present spaced wall sections of a chamber in which a pair of meshing gears 24 and 26 are rotatable.

The gear 24, which in this instance is in the upper portion of the chamber, is the driving gear, and is keyed to the drive shaft 28. This drive shaft is provided with a reduced stub end, which is mounted within an antifriction roller bearing 30, and the opposite reduced end of the shaft is mounted within a similar anti-friction bearingy 32. This last mentioned reduced extremity of the shaft extends through a suitable stuiiing box 34, y

which serves to prevent leakage from within the pump chamber along the peripheral surface of the shaft, and the outer extremity of said shaft is adapted to receive any suitable driving mechanism (not shown) The gear 26 which meshes with and is driven by the gear 24 is secured to and rotatable with a sleeve 36, which extends to the left of the gear 26, Figure 2, so as to be received by a suitable anti-friction bearing 38, which is mounted within the end casing 16.

The,opposite end of the sleeve 36 is shorter and merely extends throu h the spacer plate 14, and this extremity of t e sleeve is mounted upon a stub shaft 40 and is secured to said shaft as by means of a suitable pin 42. The reduced outer extremity of this stub shaft is rotatable within an anti-friction roller bearing 44, as'clearly shown in Figure 2. Thus it will be apparent that the gear 26 is journaled within the anti-friction bearings 38 and 40 through the agency of the supporting sleeve 36 and the stub shaft 40.

Extending within the' sleeve 36 and' mounted within a bearing section 46 of the end casing 16 is a valve member 48. This valve member 48 is of cylindrical construction and is secured against longitudinaldisplacement by means off a locking screw 50 which extends through the bearing 46 and into an annular groove 52 formed in the valve 48. The outer extremity o'f the valve member 48 carries an adjusting lever 54 which is employed to oscillate the valve member for purposes of adjustment, as will later more fully appear. A central longitudinal passageway or port 56, which is provided Within the valve member 48, communicates at its outer extremity with a suitable pipe line or duct 58, and the inner extremity of said passageway 56 communicates with a pair of radial ports 60 and 62. These radial ports communicate at their outer extremities with a common enlarged peripheral port 64. These valve ports are arranged to communicate successively with radial ports 68 and 68a provided in the gear 26.

The radial ports or ducts 68, `as clearly shown in Figure 3, extend radially from the peripheral surface of -the valve member 48 to the bottom of the spaces between the teeth 70 of the gear 26, while the outer extremities of the radial ports 68a terminate at the outer ends of said gear teeth. In this connection it is to be understood that the teeth 7 0 of the gear 26 and complementary teeth 70a of the driving gear 24 are of a modified involute construction and diiier from conventional gear tooth constructions, in that the tooth of one gear is adapted to extend wholly within the companion space in the complementary gear. In other words,.no clearance, except possibly a slight running clearance, is provided between the outer extremity of each tooth and the bottom of the space in the complementary gear into which the tooth extends. This arrangement is clearly shown in Figure 6.

Consider now that fluid, such as oil, is introduced through a pipe line 72, which communicates with the intake chamber section 74, Figure 3, and that the gears are rotating in the direction indicated by the arrows. As viewed in Figure 3, the upper driving gear rotates in a clockwise direction and the lower driven gear in a counter-clockwise direction. Fluid from the intake chamber section 74 is carried by the gear teeth 7 O and 70a to the pressure or outlet chamber section 76. From this chamber section 76 the fluid may pass outwardly through a suitable pipe line 78. Fluid which may be'trapped between the gear teeth, as for example, the fluid which may be carried into the area 80, shown in Figure 3, will be free to pass through the companion radial port or duct 68a, which at that particular instant serves to establish communication between this area 80 and the central valve passageway 56 through the medium of the radial valve ports 60 and 62. Likewise, trapped fluid may be discharged through the next adjacent radial port 68, which also communicates with the central valve passageway 56. In this manner the fluid which is trapped between the meshing teeth is salvaged and directed into association with the central valve passageway, which may be connected through the agency of the pipe line 58 to any point where fluid under pressure is required. In other words, in addition to displacing fluid under pressure through the pipe line 78, I am able to supply -fluid under another pressure to a second circuit. As state'd'above, in conventional type of gear pum s clearance is provided between the gear teet for the purpose of allowing a certain amount of slippage between the outlet and intake chamber section. If such slippage does not take place, the conventional gear pump is rendered functionally inoperable because of the development of high fluid pressures between the meshing teeth. By my improved construction I am able to put into practical use the trapped fluid which would otherwise be returned to the low pressure side of the pump. That is 4to say, instead of losing the propelling effectiveness of the trapped fluid, I am able to employ this fluid under pressure for practical purposes.

By adjusting the position of the lever 54, I am able to vary the position of the enlarged port 64 with respect to the gear 26. If, for example, the salvaged fluid shouldnot be desiged at a predetermined interval, said. fluid can be returned to-the intake chamber Section 74 by merely adjusting the position of the enlarged peripheral valve port 64. This is accomplished by shifting the adjusting lever 54. Likewise, if more than the salvaged fluid is desired within the circuit connected to the central valve passageway 56, the valve port 64 may be swung to the right, Figure 3, to establish communication between the chamber section 76 and the central valve passageway 56.

To further reduce the possibility ofheat development, I provide the outer extremities of the gear teeth with recesses 84, which facilitate the displacement of fluid from between the teeth into Vthe radial ports 68 and 68a. The recesses 84, as shown in Figure 2, extend over a greater portion of the face of the teeth ,70, and thus provide an effective fluid conducting passageway which communicates with the radial ports. In solving the problem of reducing heat developed as a result of fluid pressure between the gear teeth, it is my idea to conduct the fluid away from the gear teeth as quickly as possible, and without necessitating the passage of said fluid through restricted orifices. The recesses 84 cooperate with the radial ports and the valve ports to effect thequick and unrestricted passage of fluid into the central valve passageway 56.

In order to more clearly disclose the structural characteristic of the meshing surfaces ofthe teeth in the gears, I have shown in Figure 6 how these surfaces conform substantially with an arc A o f a circle, the radius of which is designated by the letter B. This structural characteristic of the teeth enables them to experience a rolling contact throughout the entire height thereof and affords tooth contact of a nature which precludes the slippage of fluid from the high to the low pressure chambers past the meshing teeth. Furthermore, this construction enables each tooth to fill the bottom space between companion teeth, as clearly indicated in Figure 6, thereby positively ejecting all of the trapped fluid into the central valve. Such a tooth structure materially reduces fluid heating otherwise occasioned during the meshing of gear teeth and positively prevents slippage past the Imeshing teeth.

From the foregoing it will be apparent that my invention contemplates the provision of a fluid propelling lnechanism of the gear pump type, which is capable of simultaneously producing a plurality of fluid pressures in separate circuits. The fluid in the circuit which connects with the pipe line 78 is of one pressure, and the fluid in the circuit which is LII connected with the pipe line 58 is of another 1 pressure. Obviously', the degree of fluid pressure inthese circuits will depend upon the particular structural arrangement of the pump elements which are employed. The pump structure is very compact and rigid and is capable of being set up or mounted in any convenient place with a minimum amount of effort. The parts constituting the pump are few in number and are structurally arranged so as to facilitate the assembly or dismantling of the parts. This pump,- like the pump disclosed in -my co-pending aplication, is far superior in operating characteristics to the types of gear pumps which I have known to be in common use, in that fluid slippage or by-passing from the high pressure to the low pressure side of the pump is eliminated, and the development of heat due to fluid pressure between the gear teeth, 1s reduced to a minimum. By the conveniently operable valve mechanism, I am able to direct the salvaged fluid into any desired channel or circuit, and by adjusting said valve I am able to control the' displacement of this salvaged fluid. In other words, my invention provides what might be termed a twopressure or multi-pressure fluid pump inasnmch as said pump is capable of supplying two circuits with fluid under different pressure conditions. Adjustments 1n the valve may be -made when the pump 1s operating, as well as when the pump is stationary. Obviously, by eliminating the slippage of fluid from the high to the low pressure chambersections, I am able to build up a high suction in the intake side of the pump chamber, and thereby enable fluid to be drawn from 'a considerable distance when such action is desirable. My improved fluid propelling mechanism may be operated continuously over a long period of timewithout subjecting the fluid to any appreciable 1ncrease in temperature, and obviously, this renders my pump decidedly practical in connection with devices, such as machinery for shop use, for lubrication of internal combustion engines, and for many other practical purposes. j

My invention presents a pumping mechanism in which fluid -may be uniformly displaced as distinguished from devices 1n which stuttering or pulsating non-umform displacement of fluid takes place. Umformity in fluid displacement is essential when pumps are to be employed for propelling purposes, as, for example, 1n propelling elements of machine tools and the like. In such instances -my invention provides a very desirable economical and highly efficiently operable pumping device.

From the foregoing description it is apparent that my invention contemplates the provision of means, whereby a single generating source is provided, namely, the gears 24 and 26, deliver fluid to the usual compression side of said gears, which may be connected with a fluid circuit through the agency of a pipe line 78. The fluid is delivered to this pipe line at a controlled pressure, and, in addition to said circuit, I provide means for directing fl lid from a plurality of chambers, namely( the chambers presented between the meshing gear teeth, to a second circuit at a different pressure with respect to the first mentioned circuit. Both of these circuits convey fluid to a point outside of the compressing chamber.

Changes in the specific arrangement and form of the pump structures may be made without departing from the spirit and scope of my invention, said invention being limited only by the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A fluid propelling mechanism including a gear, a second gear meshing with and driven by said first gear, a chamber for housing said gears, said chamber having inlet and outlet fluid ports, one of said gears having passageways for relieving against fluid pressures occasioned between the meshing teeth of said gears, and a valve axially positioned with respect to the gear having the passageways and constantly communicating with the passageways in the meshing teeth for continuously directing fluid from said passageway to a point externally of said inlet and outlet ports, the meshing surfaces of said gear teeth conforming substantially with the arc of a circle whereby to more effectively seal fluid trapped during the meshing of said teeth. 2. A fluid propelling mechanism including a pair of meshing gears, a chamber for housing said gears, said chamber having an intake port and an outlet port, and means including passages terminating at the outer Aends of and between said teeth, for simultaneously conveying fluid trapped between a plurality of chambers presented by the meshing teeth of said gears to a point positioned externally of said gear chamber, whereby to relieve against the fluid pressure and to salvage the trapped fluid.

3. A fluid propelling mechanism including a chamber having intake and discharge sections, a pair of meshing gears within said chamber for receiving fluid from the intake section and for subjecting said fluid to increase pressure in the discharge section, at least one of said gears having passages for simultaneously conducting fluid away from a plurality of chambers presented bythe meshing teeth, and a valve for directing fluid from said passages, whereby said conducted fluid may be employed as an independent propelling medium.

4. A fluid propelling mechanism including a chamber having intake and discharge sections, a pair of meshing gears within said chamber for receiving fluid from the intake section and for subjecting said fluid to increased pressure, a plurality of radial passageways in one of said gears for conducting fluid away from the meshing teeth, said passageways being arranged to relieve against heat producing pressure during the meshing of said teeth, and a central valve communieating with the passageways in the vicinity of the meshing teeth for controlling the displacement of such conducted fluid to a point externally of said gear chamber.

5. A fluid propelling mechanism including a chamber having intake and outlet sections,

a pair of meshing gears housed within said chamber` for receiving fluid from said intake section and for subjecting said fluid to increased pressure at said outlet section, one of said gears having a plurality of radial ports for conducting fluid, away from the meshing teeth of said gears, and a central shiftable valve adapted to communicate with 'said radial ports for controlling the displacement of such conducted fluid, said valve having a longitudinal paageway and a radial port for establishing communication between said longitudinal passageway and said radial ports. v

6. A fluid propelling mechanism including a chamber having intake andA outlet sections, a pair of meshing gears housed within Said chamber for receiving fluid from said inlet section and for subjecting said fluid to increased pressure in said outlet section, a plurality of passageways in one of said gears for conducting fluid away from the meshing teeth, and a central valve shiftable for controlling the displacement of such conducted fluid, said valve having a peripheral port registerable with the passageways in the vicinity of the meshing teeth for receiving said conducted fluid and a radial port communicating with said peripheral port for conducting fluid from said passageways to a central passage of said valve communicating with a point externally of the chamber.

7. A fluid propelling mechanism including a chamber having inlet and 'outlet sections, a pair of meshing gears within said chamber for receiving fluid from said inlet section and for subjecting said fluid to increased pressure in said outlet section, a plurality vof radial ports in one of said gears for conducting fluid away from the meshing teeth, and an oscillatory valve having a peripheral port, a radial port connected with said peripheral port for receiving fluid from the radial ports in said gear, and a central passageway connected with said radial port, whereby fluid conducted from the radial ports in said gear may be employed as an independent propelling medium, the shifting of the valve serving to vary the displaceemnt of fluid from the outlet section.

8. A fluid propelling mechanism lincluding I a chamberhaving inlet and outlet ports, a pair of lmeshing gears housed within said chamber, and a plurality of radial passageways positioned between the. working flanks of the teeth in at least one of said gears for relieving against fluid pressures occasioned between the meshing gear teeth, the teeth in at least one of said gears being provided only along the outer extremities thereof between the working flanks with a recess positioned intermediate the sides of the teeth and communicating with said radial passageways to facilitate the withdrawal of fluid through said radial passageways.

9. A uid propellin mechanism including a chamber having in et and outlet ports', a pair of meshing gears housed within said chamber, and a lurality of radial passageways positioned Ibetween the workin flanks 7 of the teeth in at least one of sai gears for relieving against fluid pressures sioned between the meshing gear teeth, th teeth in at least one of said gears being provided only alongthe outer extremities thereof between the working flanks with recesses extending over less than the entire len h of said teeth and communicating with sa1d radial passagewa s to facilitate the withdrawal of fluid throug said radial passageways.

10. A gear pump including a housin a pair of meshing gears within said housing, radial passageways extending to the outer ends of the teeth for conducting fluid away from the meshing teeth, and peri heral recesses extending ongitudinally on y partially across the crown of the teeth between the working flanks in at least one of said gears which communicate with said radial passageways to facilitate the withdrawal of fluid from between the meshing teeth and thereby relieve against the development of fluid pressure.

11. A gear pump including a housing, a air of meshing gears mounted within said ousing, said gears bein sealed against leakage at the sides thereo and a pluralityof radial passageways `enclosed within at least one of said gears for relieving 4against fluid pressures ot erwise'occasioned between the meshing gear teeth, the teeth in at least one of said gears being provided with a peripheral recess ositioned between the worklng flanks which) communicates with said radial passageways to -facilitate the withdrawal of fluid through said passageways and thereby relieve against the development of fluid' pressure.

12. A gear pump including a housing, a pair of meshing gears mounted within said housing, a plurality of radial passageways provided in at least onev of said gears for rev lieving against fluid pressu-res otherwise oc-` casioned between the meshing gear teeth, longitudinal recesses positioned between the teeth of at least one of said gears for communicating with certain of said radial passageways, and longitudinal recesses provided at the outer end of the teeth and between the working flanks thereof in at least one of said gears for communicating with certain of said radial passageways, whereby to facilitate the withdrawal of fluid through said passageways and thereby relieve against the development of fluid pressure.

13. A gear pump including a housing, a pair of meshing gears mounted within said housing, at least one of said gears having radial passageways enclosed within and terno minating at the outer ends and between the\- working flanks of the gear teeth, at least one of said gears having radial passageways terminating between the teeth thereof, all of said passageways serving to relieve against the development of fluid pressure between meshing teeth, and longitudinal recesses provided in at least one of said gears between the working flanks of the gear teeth and communicating with said radial passageways to acllitate the withdrawal of fiuid from between the meshing teeth through said radial passageways.

14. A gear pump including a housing, a pair of meshing gears mounted within said housing, said housing having inlet and outlet ports, the meshing surfaces of said gears conforming substantially with an arc of a circle and the tooth of one gear adapted to extend within and completely fill the companion bottom space between the teeth ofthe other gear, at least one of said gears having radial passages for receiving all of the fluid from between the meshing teeth thereof, and means communicating with the passages 1n the vicinity of the meshing teeth for directing said fluid to a point independent of the discharge port and thereby supplying a uniform flow of fluid which may be employed independently of the fluid from the discharge ort. p 15. A gear pump including a housing, a pair of meshing gears mounted within said housing, said housing having inlet and outlet ports, at least one of said gearshaving a plurality of radial passages termmating at the outer ends of and between the teeth, and a single valve for directing fluid from the p assages located in the vicinity of the. meshing teeth of said gears to a point positioned externally and independently of said outlet port.

16. A gear pump including a hous 1ng, a pair of meshing gears positioned wlthin sa id housing, an inlet port for directing fiuid to said gears` an outlet port for directing fiuid compressed through the action of the teeth in carrying fluid from the intake to the out- `let side of the pump, radial passages provided in at least one of said gears for salvaging fluid which becomes trapped between the meshing gear teeth, a valve member positioned centrally with respect to the gear having the radial passageways for direc-ting fluid from saidy passageways to a point externally of the/outlet port, and bearing means for taking up the radial load experienced by the gear having the passages whereby to relieve saidvalve from such radial load.

- 17. A gear pump including a housing, a pair of meshing gears positioned within said housing, aninlet port for directing fluid to said gears, an outlet port for directing fluid compressed through the action of the teeth in carrying fluid from the intake tothe outlet side of the pump, radial passages provided in at least one of said gears for salvaging fluid which becomes trapped between the meshing gear teeth, and an oscillatory valve member positioned centrally with respect to the gear having the radial passageways for directing fluid from said passageways to a point externally of the outlet port, the shifting of the valve serving to vary the displacement of fluid from the outlet port.

18. A gear pump including a housing, a pair of meshing gears positioned within said housing, an inlet port for directing fiuid to said gears, an outlet port for directing fluid comprsed through the action of the teeth in carrying fluid from the intake to the outlet side of the pump, radial passages provided in at least one of said gears for salvaging fluid which becomes trapped between the meshing gear teeth, a shiftable valve member positioned centrally with respect to the gear having the radial passageways for directing fluid from said passageways to a point externally of the outlet port, the shifting of the valve serving to vary the displacement of fiuid from the outlet port, and control means connected with said valve, said control means being positioned externally of the pump housing forconvenient manual manipulation.

19. A gear. pump including a housing, a pair of meshing gears positioned within said housing, an inlet port for directing fluid to said gears, an outlet port for directing fiuid compressed through the action of the teeth in carrying fluid from the intake to the outlet side of the pump, radial passages provided in at least one of said gears for salvaging fluid which becomes trapped between the meshing gear teeth, and a shiftable valve member positioned centrally within the gear having the radial passageways and having a port of sufiicient width circumferentially to communicate with at least two of said passageways simultaneously and a passage for conducting fluid from the port to a point externally of the pump housing, the shifting or' the valve serving to vary the displacement of fluid from the outlet port.

20. .A fluid propelling mechanism including a gear, a second gear meshing with the first gear, at least one of said gears having radial passages. a chamber for housing said gears, said chamber having inlet and outlet ports, and means in one of said gears constantly communicating with the passageways in the vicinity .of the meshing'teeth for directing fluid from between said meshing teeth to a point dis-posed externally of said ports, said passages being arranged to relieve against heat producing pressures during the meshing of said teeth.

21. In a fiuid propelling mechanism including a chamber having intake and outlet sections, a pair of meshing gears housed within said chamber for receiving fluid from said intake section and for subjecting said fluid to increased pressure, a plurality of radial passageways in one of said gears for conducting fluid away from the meshing teeth, and a shiftable valve having a passageway extending longitudinally thereof designed for communication with a point positioned externally of the inlet and outlet sections, said longitudinal passageway being adapted to communicate with said radial passageways for controlling the displacement of fluid conducted therethrough and for conducting fluid from said passageways to a point positioned externally of said intake and outlet sections.

22. A fluid propelling mechanism including a chamber having inlet and outlet seetions, a pair of meshing gears within said chamber for receiving fluid from said intake section and for subjecting said fluid to increased pressure in the outlet section, a plurality of radial ports in at least one of said gears for conducting fluid away fromV the meshing teeth, and a central adjustable valve adapted to communicate with said radial ports for controlling the displacement of said conducted fluid to a point externally of said gear chamber, said Valve in one position of 'adjustment adapted to establish communication between an external point and said outlet section.

23. A fluid propelling mechanism including a chamber having inlet and outlet sections, a pair of meshing gears housed within said chamber for receiving fluid from said inlet section and for subjecting said fluid to increased pressure in said outlet, section, a plurality of radial ports provided in one of said gears for conducting fluid away from the meshing teeth, a shiftable valve for controlling the displacement of such conducted fluid, and means connected with said valve for conducting fluid therefrom to a point externally of the gear chamber, said Valve in-one shifted position serving to establish communication between a point externally of said chamber and the outlet section.

In witness whereof, I have hereunto subscribed my name.

ERNEST J. SVENSON. 

